Update rsa_cipher.py by replacing %s with {}

Author: rohan472000

Diff for: ciphers/rsa_cipher.py

@@ -76,7 +76,7 @@ def encrypt_and_write_to_file(
     key_size, n, e = read_key_file(key_filename)
     if key_size < block_size * 8:
         sys.exit(
-            "ERROR: Block size is %s bits and key size is %s bits. The RSA cipher "
+            "ERROR: Block size is {} bits and key size is {} bits. The RSA cipher "
             "requires the block size to be equal to or greater than the key size. "
             "Either decrease the block size or use different keys."
             % (block_size * 8, key_size)
@@ -101,7 +101,7 @@ def read_from_file_and_decrypt(message_filename: str, key_filename: str) -> str:
 
     if key_size < block_size * 8:
         sys.exit(
-            "ERROR: Block size is %s bits and key size is %s bits. The RSA cipher "
+            "ERROR: Block size is {} bits and key size is {} bits. The RSA cipher "
             "requires the block size to be equal to or greater than the key size. "
             "Did you specify the correct key file and encrypted file?"
             % (block_size * 8, key_size)